效果：
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>双语导航/导航中鼠标经过变换文字</title>
<style type="text/css">
* { margin:0; padding:0; }
.nav { list-style:none; 500px; height:30px; background:#333; margin:50px auto; }
.nav li { float:left; 100px; height:30px; line-height:30px; text-align:center; }
.nav li a { display:block; height:30px; overflow:hidden; text-decoration:none; color:#fff; font-size:14px; }
.nav li span { display:block; height:30px; }
.nav li a:hover { background:#444; }
.nav li a:hover span { margin-top:-30px; } /*.nav li a:hover span { display: none; }也能同样达到效果（元素移动或是元素不会被显示）*/
</style>
</head>
<body>
<ul class="nav">
<li><a href="#"><span>Home</span>网站首页</a></li>
<li><a href="#"><span>About</span>关于我们</a></li>
<li><a href="#"><span>News</span>新闻动态</a></li>
<li><a href="#"><span>Product</span>产品展示</a></li>
<li><a href="#"><span>Contact</span>联系我们</a></li>
</ul>
</body>
</html>
原文摘自http://www.cnblogs.com/huige728/archive/2012/05/02/2479307.html